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Post by kenrick on Nov 20, 2005 1:24:06 GMT 8
2. "In nature, space is vital", using your knowledge about animals, discuss the statement and give examples. ;D ;D My exam questions this morning..... ;D ;D and this is Uni Year 3 exam..... >.< I will give question 2 a shot first. Don't really know what it demands, but I will attack selection pressures and natural demands.In the context of natural selection, space has often been a regulatory means of stabilising the population numbers. An exponential increase in the population will result in a sudden lack of space-causing problems such as competition for food and the spread of disease. For example, in the late 19th century in Australia, where there was a sprout in the number of rabbits, there was also a widespread of the disease of myxomatosis. Rabbits were in such close proximity to each other that the virus could be easily spread from one organism to the other; hence the probability and ease of the disease spreading increases. In general, lack of space implies that there is an increased chance of competition. Organisms have to compete for reproductive partners, food and space for shelter to satisfy their basic needs. The population will only stabilise at a number in which the space for each organism is adequate-i.e. there isn't a very high chance for competition for basic needs. For question 1-on coconut trees, I think that the website www.prayogpariwar.net/Coconut_Palm.htm says it all. ;D Thanks hoyohoyo for the questions.
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Post by hoyohoyo on Nov 20, 2005 3:37:58 GMT 8
Re: Kenrick's respone on chloropyll.... Evolutionary biologists generally believe that both Animals and Plants shares common ancestor.... so you can actually postulate that the common ancestor of the Animals and Plants did not have chlorophyll.... and thereafter Chlorophyll or Chloroplast actually developed after the diversion of animalia and plant....~~ Also.... it is postulated that organelles such as Mitochondria and Chlorophlast were evolved due to errr... i've forgot the term..... basically means "Higher" cells eaten those "lower" cells that were capable to run Aerobic respiration or photosynthesis and slowly the "eaten" cell was adapted into the "higher" cell.... and evolves to become presence mitochondria or chloroplasts.... So it is explainable through this theory that the ancestor of plants..... well.... the nenek moyang of Algae obtained chloroplasts and passed down to the whole tree..... while the other branch of the evolutionary tree did not obtain chloroplasts....~~ Perhaps another more interesting question is..... What if Animal obtains Chloroplast??? ![;)](//storage.proboards.com/forum/images/smiley/wink.png)
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Post by hoyohoyo on Nov 20, 2005 3:46:10 GMT 8
LOL.... as my subject was on Live form and function..... so the space here is more of Biological.... ![;)](//storage.proboards.com/forum/images/smiley/wink.png) So the answer could be more Form and function.... our body form..... and so on... ![:)](//storage.proboards.com/forum/images/smiley/smiley.png) Your answer is cool enough.... ![:)](//storage.proboards.com/forum/images/smiley/smiley.png) Good job and you really got that enthusiast huh... ![:D](//storage.proboards.com/forum/images/smiley/grin.png)
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Post by TensionDBSK on Nov 20, 2005 15:47:26 GMT 8
Re: Kenrick's respone on chloropyll.... Evolutionary biologists generally believe that both Animals and Plants shares common ancestor.... so you can actually postulate that the common ancestor of the Animals and Plants did not have chlorophyll.... and thereafter Chlorophyll or Chloroplast actually developed after the diversion of animalia and plant....~~ Also.... it is postulated that organelles such as Mitochondria and Chlorophlast were evolved due to errr... i've forgot the term..... basically means "Higher" cells eaten those "lower" cells that were capable to run Aerobic respiration or photosynthesis and slowly the "eaten" cell was adapted into the "higher" cell.... and evolves to become presence mitochondria or chloroplasts.... So it is explainable through this theory that the ancestor of plants..... well.... the nenek moyang of Algae obtained chloroplasts and passed down to the whole tree..... while the other branch of the evolutionary tree did not obtain chloroplasts....~~ Perhaps another more interesting question is..... What if Animal obtains Chloroplast??? ![;)](//storage.proboards.com/forum/images/smiley/wink.png) Aaahh..the endosymbiotic hypothesis! Is that what you're referring to hoyohoyo? The theory refers to how eukaryotic cells are a symbiosis consortium of prokaryote cells am I not right? The theory mentioned about how it was possible that the aerobic bacteria invaded the original prokaryote cell (which was believed to have been very much like an anaerobic amoeba) through endocytosis and then each performed mutually benefiting functions? It was when the external world experienced a change to become more pro-oxygen that the bacteria begun to take former function in the prokaryote cells and hence brought about eukaryotic cells and these bacteria endosymbionts were referred to as mitochondria right? Just that in plants, photosynthetic bacteria invaded the cell and hence functioned as what we call now the chloroplasts. Is it impossible for the animalia kingdom to obtain chloroplast? Based on this endosymbiotic theory, I don't deem it too ridiculous for our future generation innumerable years to come (that's if a form of life still exists) to obtain chloroplasts..after all, it is based on mutual benefits.. Do we actually need chloroplasts to be autotrophic? What is in chloroplasts that's so special? And why are chlorophylls green again? (Don't kill me for asking this kor!)
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Post by shinghui on Nov 20, 2005 16:31:53 GMT 8
ya..the population of increased number of rabbits during tat period 1859 is very shocking.. 12 pairs of rabbits are brought and the people who brought them do not know that the conditions they are going to live was an abundance and there were less predators to feed them..so their numbers increased until they affect the grazing for sheep.
As Kenrick has mentioned..environmental factors such as abiotic and biotic factors can keep their number down...the population of rabbits is like an oscillating graph.. as the environmental factors such as myxomatosis made the numbers of rabbits down..but after a period..the number will be increase again.
Some of the autotrophs do not depend on light energy thus they do not need chloroplast such as nitrifying bacteria..they are chemoautotrophs.. Chloroplasts contain chlorphyll which are photosynthetic pigments which will adsorb light (red and blue violet) they reflect green light..thus they are GREEN in colour..
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Post by TensionDBSK on Nov 20, 2005 17:23:18 GMT 8
Thanks shinghui for the detailed explanation. Specifically, I was actually wondering whether it was possible to be photosynthetic without the existence of chlorophyll, maybe by having pigments almost similar to clorophyll? And why does photosynthesis occur rapidly with the presence of red and blue light? Is it relevant to the wavelength of light most strongly absorbed by the accesory pigments hence transferred to chlorophyll a? The SPM books only tell you that red and blue/violet light are most effective in photosynthesis. Is it also related to the potential for transfer of electrons?
Is there a reason for green light to be reflected and not absorbed by chlorophylls? What exactly is the structure of a chlorophyll that makes it reflect the green wavelength?
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Post by shinghui on Nov 20, 2005 18:03:05 GMT 8
lol!!i am studying photosynthesis now! okiez.. they are other photosynthetic pigments that adsorb different wavelengths of light. for chlorophylls they are chlorophylls a nd b..a adsorb yellow green while chlorophyll b adsorb blue green colour the other pigment such as beta carotene adsorb orange colour and xantophlyll adsorb yellow colour. The photosynthetic pigments adsorb the light energy and convert it to chemical energy and the light energy excites the electrons in the pigment molecules. The electrons then return to their unexcited stage and the adsorbed energy is transferred to surrounding as thermal energy and as light at a longer wavelength. The book writes different pigments adsorb different wavelengths of light oh. i dunno which is the exact structure that make it reflects wavelength but photosynthesis takes place in palisade mesophyll
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Post by kenrick on Nov 20, 2005 18:13:38 GMT 8
Re: Kenrick's respone on chloropyll.... Do we actually need chloroplasts to be autotrophic? What is in chloroplasts that's so special? And why are chlorophylls green again? (Don't kill me for asking this kor!) Well, for the first time, I won't kill you. The detailed answer is far beyond your syllabus. In SPM, you have studied as much as the presence of grana as stacks of thylakoids. What you do NOT know is that the thylakoid membrane is not as simple as it looks. It actually has many photosynthetic pigments on it. When light strikes the membranes, it 'excites' the electrons in the photosystem (accessory pigments +primary pigment-reaction centre): read up a little. Now, you certainly know about the absorption and reflection of light thing. What makes the green totally reflected is a bit harder to explain online. Refer to the following two: (i) Energy levels of electrons in photosystems (ii) Relate to absorption spectrum and spectrum of activity. Re: Why animals don't have chloroplastsVery interesting thought, hoyohoyo. Never really looked at the question from that point of view. It would be quite interesting to picture mammals as a whole being autotrophic. I am starting to think about what will happen to the food chain and transfer of energy of the trophic levels. Two extensions of the question which have to be considered: (i) Will the whole pyramid of biomass and numbers collapse? (ii) Will there be temporary selection in favour of all living things, as the predator-victim relationship is no longer necessary? What happens to the Earth when there is such an exponential growth in population? *Starting to think about hoyohoyo's question on space being vital*
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Post by shinghui on Nov 20, 2005 22:47:54 GMT 8
i wan to ask why people who are heterozygous for sickle cell anemia are less likely suffer from malaria? izzit because there are something that the mosquito dun like their blood?
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Post by seening on Nov 21, 2005 1:19:52 GMT 8
wah really hard question. is it bcos the anemia patient have sum kind of antibody tat can kill the malaria ?
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Iris
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Post by Iris on Nov 21, 2005 1:36:07 GMT 8
anyone wants pmr objective paper answers just add me in msn i'll give da answers...for Sejarah BM1 ENG1 MATHS1 GEO SC1... KH is soalan tertutup so cannot.. thx~
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Post by kenrick on Nov 21, 2005 9:55:26 GMT 8
i wan to ask why people who are heterozygous for sickle cell anemia are less likely suffer from malaria? izzit because there are something that the mosquito dun like their blood? Hi shinghui. I don't have the full answer, but I will do my best. As you know, the sickle shape of the red blood cell is caused by a 'swap' in the 6th amino acid of the beta-polypeptide which makes haemoglobin. (glutamic acid-valine). This changes the specific tertiary conformation of the red blood cell as a whole. Plasmodium sp. starts 'breeding' in the erythrocytes, so it has to bind with the red blood cell membrane to enter. The sickle shape of the haemoglobin disables this binding, so plasmodium sp. cannot enter the red blood cells. As such, any individual with the sickle cell allele (heterozygous or homozygous) is safe from malaria. Of course, if he/she is homozygous sickle cell, he/she will suffer from serious anemia.
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Iris
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Post by Iris on Nov 21, 2005 14:01:41 GMT 8
![;)](//storage.proboards.com/forum/images/smiley/wink.png) ..hello pinkies...PMR candidates.. here is answers for BM1.. errm..the school teacher gave it to us so i can't guarantee whether its 100% or not..sry if i am wrong.. 1 C 2 B 3 D 4 C 5 A 6 B 7 A 8 A 9 B 10 C 11 D 12 B 13 A 14 B 15 C 16 D 17 C 18 B 19 C 20 A 21 C 22 D 23 A 24 C 25 B 26 NOT SURE..MAYBE BONUS 27 B 28 A 29 B 30 D 31 A 32 C 33 A 34 D 35 A 36 B 37 A 38 D 39 B 40 C
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Post by Iris on Nov 21, 2005 14:06:46 GMT 8
MATHS 1 NOW...
1 A 2 B 3 C 4 C 5 B 6 D 7 B 8 C 9 B 10 B 11 C 12 B 13 C 14 B 15 A 16 A 17 C 18 B 19 D 20 B 21 B 22 A 23 C 24 C 25 B 26 C 27 C 28 B 29 C 30B 31 C 32A 33A 34 C 35 C 36 A 37 C 38 D 39 D 40 B
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Iris
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Post by Iris on Nov 21, 2005 14:13:54 GMT 8
SEJARAH
1 B 2D 3 C 4 B 5 C 6D 7 B 8 C 9 B 10 A 11 C 12 A 13 B 14 D 15 B 16 C 17 A 18 A 19 C 20 C 21 D 22 A 23 B 24 B 25 C 26 C 27 B 28 B 29 D 30D 31A 32C 33B 34 B 35 A 36 A 37 C 38 A 39 C 40 B 41B 42D 43A 44B 45D 46C 47A 48A 49B 50B 51B 52B 53D 54C 55C 56B 57C 58C 59B 60A
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